[Qemu-devel] [PATCH v2 2/2] [RFC] arm: program migrated guests' invariant registers with host ones

[<mjaggi@caviumnetworks.com>]

From: Manish Jaggi <manish.jaggi@cavium.com>

When KVM_SET_ONE_REG returns KVM_EINVARIANT call KVM_GET_ONE_REG to query
and then replace the particular guest invariant register value with destination
hosts register.

Signed-off-by: Manish Jaggi <manish.jaggi@cavium.com>

diff --git a/target/arm/kvm.c b/target/arm/kvm.c
index 65f867d..8cf4dc9 100644
--- a/target/arm/kvm.c
+++ b/target/arm/kvm.c
@@ -19,6 +19,7 @@
 #include "sysemu/sysemu.h"
 #include "sysemu/kvm.h"
 #include "kvm_arm.h"
+#include "standard-headers/asm-arm/kvm_para.h"
 #include "cpu.h"
 #include "trace.h"
 #include "internals.h"
@@ -37,6 +38,8 @@ static bool cap_has_mp_state;
 
 static ARMHostCPUFeatures arm_host_cpu_features;
 
+extern bool enable_hostinvariant;
+
 int kvm_arm_vcpu_init(CPUState *cs)
 {
     ARMCPU *cpu = ARM_CPU(cs);
@@ -451,8 +454,16 @@ bool write_list_to_kvmstate(ARMCPU *cpu, int level)
         default:
             abort();
         }
-        ret = kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, &r);
-        if (ret) {
+	ret = kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, &r);
+	if (enable_hostinvariant && ret == -KVM_EINVARIANT) {
+		/* Update Guest invariant to match with migrated host regs*/
+		ret = kvm_vcpu_ioctl(cs, KVM_GET_ONE_REG, &r);
+		if (ret)
+			ok = false;
+		else
+                	cpu->cpreg_values[i] = r.addr;
+        }
+        else if (ret) {
             /* We might fail for "unknown register" and also for
              * "you tried to set a register which is constant with
              * a different value from what it actually contains".
-- 
1.8.3.1